Addition and subtraction with significant figures | Decimals | Pre-Algebra | Khan Academy

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Addition and Subtraction with Significant Figures
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[@andreapaulinegavino7466]

ANYONE PAUSING THE VIDEO AND LOOKING IF IT'S REALLY 3.7? lmao it made my day

[@priscillabenyam9642]

Yeah right now I paused it and I just didn't understand how it is 3.7

[@Zee-hc1ld]

@@priscillabenyam9642 same

[@rajdeepsingh8368]

its not he made a mistake

[@gh3stly627]

It’s 3.6 right?

[@gh3stly627]

@@rajdeepsingh8368 ?

[@super0chick]

At 3:00 The addition rounding up should be 3.6 NOT 3.7 (from rounding 3.56)

[@DanielReyes27781]

Thank you so much

[@jasongrove2092]

Gotta love that edit! 3.6 NOT 3.7 lol

[@pineapplekun]

Is that part edited? I’m not able to see the edit on my iPad :(

[@SahilSharma-ld4dg]

3.6 not 3.7

[@statejake103]

Khan Academy, the soul reason I pass exams

[@jiboyoseo]

*coal jk

[@matv202]

not including your english exam...

[@j7055]

sole* it’s a common malapropism though lol

[@maskedmarvyl4774]

Could it be the sole reason? Or the Sol reason? Or is it really the soul reason, like "The Sooooooouuuul Train!!"

[@FreeThinkingRichard]

Don't just think about getting a good grade in your Chemistry Class. Science is based on what you can PROVE. This is essential when showing results of something so that you can have no 'guesses'.

[@LexiTDanh]

I noticed the 3.7 too lol but I got it! Human error. It happens-love this channel regardless

[@pacman4521]

I love that Khan academy has answers for the exact things I'm confused about.

[@TechnoTina56]

I finally understand what my chem teacher is talking about! I feel ready for my quiz tomorrow! Thank you so so so very much!

[@OB_Music51]

i also have a quiz tmr about this lol

[@Relax4now]

Dang you have a job or something now?

[@OB_Music51]

@@Relax4now rt it’s from like 9 years ago but am in high school

[@pwryasar8900]

Same I have a quiz in one min

[@geetugupta7244]

Christina what happened in 10 years?

[@JosieShufflez]

There is a log on a calculator for sig figs. You hit log then SCI for scientific notation. Then whatever the decimal is shows the sig figs for that number. It's quite helpful really. This is used if you struggle with scientific notation or if you don't have a calculator handy.

[@COCCmath]

Question: in the "1.26 + 2.3" example, we learn that you can only keep the least number of sig figs held by the input measurements. However, since you're adding them, they must have the same unit (say, meters)...if the unit is the same, and if you;re taking the measurements yourself, why would you have different precision if you're measuring two different lengths? If you had hundredths' precision for the first measure, wouldn't you get hundredth's precision for the second? (I suppose an answer could be, "Well, what if one person does the first measure and another does the second, and they use different instruments", but that seems a little weird) Sorry if this is a dense question.

[@lzlnchl]

3.56=3.6 not 3.7

[@ahsanmohammed1]

Over all, clip was helpful. Learnt something. I’m grateful to Sal.

[@awol9914]

Thank you Khan Academy for all the great videos.

[@theresap2920]

God bless you! This is exactly what I've been looking for!

[@ella7939]

Bro am I the only one who finds the narrator funny when he talks XD. Also, Khan Academy always explain lessons easily. This is why me and my parents love it.

[@sunilchandel4288]

You are absolutely right

[@chiramana_]

I can't thank you enough 🙏🏼 May God bless you & Keep growing 🌻

[@kylec.8693]

Thanks so much! Helped me with my Chem homework.

[@JamesBrodski]

Great video! Just what I needed.

[@mayanelson5586]

Thank you! This helped so much!

[@chardoneyjuarez]

I have been using Khan Academy since my sophomore year of high school. I am a sophomore in college now and I am still passing these semesters!♡

[@dylank9746]

True

[@noaha2066]

update? It's been 5 years lol, but how's it going?

[@famguy218]

Finally I learn this. Chemistry midterm in an hour, this was the only thing I didn't know.

[@aredee7]

How'd you do, big guy?!!?!

[@erenYeager303]

He is a family guy rn

[@XxAlex530xX]

Bless the Internet. I can literally mater anything if I put in the time and effort and online teachers making it simpler :).

[@abdallababikir9154]

master*

[@XxAlex530xX]

@@abdallababikir9154 haha yes master

[@Biohippie]

you are the greatest!

[@Felicityfergun]

Ahhhh keep making more chem videos ! Your awsome

[@caramelcubez8166]

This helped me so much with my Chem 1 homework.

[@MisterDumbNuts]

What application do you use in your videos? It's so cool!

[@FishFrog_Animations]

thanks a lot for the help!

[@judejameson3863]

If only you were my teacher

[@Science_AnimoPhotography]

Hello sir i have a question Why do we consider least decimal places when doing addition or subtractio n rather than least number of significant digits as considered in multiplication or division.

[@shlovaski8393]

What if u multiply, then divide , then multiply, then divide. Would u still use the term with the lowest sig fig?

[@YouKnowMeDuh]

2:50 When sig figs get a power-up and become stronger lol

[@GetMeThere1]

So....what do you do if you need to make a long series of calculations, involving m/d AND a/s? Do you: 1) Wait until the very end of all calculations before "rounding to..." and 2) Always round to the "least precise," because that's the most stringent, and you did have some a/s operations in the series?

[@ISOFM]

What happens if you have to subtract the numerator, and then divide? Ex: (19-9.25)/(7.4x2.26)? Do you keep the Sig Figs from the 19,so only one SF in total? Of does dividing trump the add/Subtract, and you use the 2 sig figs (from the 7.4) (9.75)/16.724)?

[@ryostyles9904]

You definitely have to solve the numerator for the significant figures first then divide.

[@WSCOMPUTER]

@smicha7 I found the answer in the next video - this is multiplying by a pure number. Great job Sal!

[@sossoreal24]

It's 3.6 not 3.7

[@06050813able]

thank you very much it helped me alot

[@minhandrew3305]

There was a guy who could explicitly explain what significant figures are and what do they mean for free. Ten years later, I know this guy thanks to the deadly boring lecture of my teacher at uni that I paid ~100$ for the course.

[@urname6910]

WOOOOWW this makes so much more sense

[@saohman5454]

Omg. I can't believe I just comprehended that.

[@ethanselby1074]

Man I wish you where you my teacher this makes 100% more sense explained this way, this organization is SO ridiculously helpful.

[@meghanakumar4087]

How do you add/subtract signficant figures without decimals? My teacher said you had to find the leftmost uncertain digit but I don't understand what that means?

[@amrojjeh]

8.02 + 1.0 = 9.0 Why isn't it 9.02? Well it is because 1.0 does not measure to the nearest 100th. It only goes to the 10th decimal digit. When your teacher is saying to find the leftmost uncertain digit, he is pretty much saying to make your answer as close to the number with the least decimal digits as possible. So 1 + 1.0 should equal 2 and not 2.0. You have to base your answer off the number with the least amount of digits after the decimal place. ==== More Examples== 19 + 1 = 20 19.01 + 1 = 20 19.01 + 1.00 = 20.01 19.1 + 1.00 = 20.1 Hopefully that answers your question.

[@kwebaa]

what app did you use to write those down?

[@Tager253]

you write so nice using a computer mouse i tried it using the mouse but my writings seems like im still in grade school but thanks for the video great help

[@TechCentralHub]

Thats exactly what I am going to write on my lab report

[@jozet]

This reminds me of a guy explaining to his wife, why his side chicks are not significant, it's because their relationship with him is ambiguous. 🤣

[@paulceltics]

@AtomFA its very useful for later stuff

[@leahharpole4880]

This guy knows everything i love him lol

[@aamirwni]

excellent

[@evat267]

Tag yourself I'm 3.7

[@spideyman6099]

Ur the bestt

[@mariaa.z2762]

What does he mean by least precise?

[@frances4740]

thank you sooooooo muchhhh :dd

[@PseudonymUnknown]

hi uhm i was wondering about a question if the problem was (0.120)(0.08206)(273.15 +23)(760)/230 would the answer be based on the least sig figs of all the numbers?

[@ManDudeYeah]

@faisalkfpm Totally, dude.

[@McLovinYourMom205]

Shouldn't it be rounded to 3.6 instead of 3.7 @ 2:56?

[@beast2808]

Yep

[@oao8227]

it's the whole numbers that still baffles me a little

[@TheBoss2288]

How about when it's mixed: (5.0x5.05)+(.005x5.0005) ??? Do you do the multi/div rule or the add/sub rule

[@dpguinee]

use pemdas (order of operations) then apply individual rules

[@timbruse]

***** Yes PEMDAS, but do not round until the final answer.

[@Sarahc366]

+Mitch Polowyszak after you do the multiplication in the parentheses, only addition is left to do, so you go by the add/sub rules

[@dakinhelen]

+TheBoss2288 Do the entire calculation and do not round off any intermediate answers. that is step 1. step 2 is to round the final answer to the least # of Significant digits if there is ANY mult or division in the calculation or to round the final answer to the same precision as the least precise number if there is ONLY addition/subtraction in the calculation. Hence, we have what I call 'low order' arithmetic (only add/subt) or 'high order' arithmetic (which includes mult/division/powers/ roots/ etc etc). When we have only low order arithmetic, we round final answer to the least precise input value when we have high order arithmetic, we round final answer to the least # significant digits.

[@maskedmarvyl4774]

I love that you filmed this in the dark and wrote in tiny fluorescent letters. It made it impossible to read. I had to listen to the audio several times to get the point. Otherwise, good explanation.

[@tiffanysydnor2691]

I thought it was only me with that 3.7 3.6 stuff

[@anonymouscopyrighter1437]

ty

[@-IIya]

3.6

[@jelly_belly101_2]

Yallmlove catching the teacher don’t you?😂

[@YourResidentPersonWhoDoesStuff]

Now I feel like maybe I won't fail Physics this year

[@johndesayuno]

No se inglés pero me funciono mucho

[@WSCOMPUTER]

24.0675 * 3 = 72.2025. If I had one significant digit (3) the result would be 7?

[@NURIACRUZ1]

3:37 should be rounded to 104 since the least sig figs is 3 digits .... i am confused somenoe help!!

[@krypticsky3545]

3.6!!!!

[@hollymuffins4277]

wait, at 2:57 shouldn't it have been rounded to 5.6, not 5.7?

[@roarmaster2]

how many videos do u make a day ?

[@vibins360]

3:00 do you mean three point 6 instead of 3.7?

[@beast2808]

Yep

[@godofredocalabroso9170]

Goshh I thought I was so dumb when thought that it's actually 3.7 lol

[@arsh5967]

That awkward moment when you're an MIT graduate but you round 3.56 to 3.7

[@jamesking9887]

did you not see the edit he put in there you idiot

[@lucdk5]

Calm down. You don't know when he edited that in, maybe it was after this comment.

[@AYUSHTVGaming]

Arsh Kohli ya it should 3.6

[@ashrayakochara2291]

What happened with the last sum

[@lukepeja7577]

3:00 it's 3.6

[@amrojjeh]

My problem is with sig figs is that it does not convert easily from multiplication to addition. If you do 2.0(2 sig figs) + 2.0, then you will get 4.0(also 2 sig figs.) However if you do 2.0 * 2(1 sig fig), which is the same thing as 2.0 + 2.0, you will get 4 (1 sig fig). That to me makes no sense. If you can explain that to me than that would be appreciated.

[@owuiniii]

Dingly Do Hi, I'm confused with that too. By any chance, did u already know the explanation for that?

[@amrojjeh]

azi xx Nope.

[@owuiniii]

Dingly Do aww too bad 🙁 my midterm exam in chem will be tomorrow tho lol anyways thank you!

[@yasmeenz6851]

Dingly Do the thing is that if you multiply 2 by 2.0, you do not know if the 2 was rounded. It could've originally been 2.1 or 1.9, which would not result in 4.0. It is true 2*2.0 is 4.0, but we don't exactly know if it really is 2.0+2.0. Say it were 2.1, then that'd be 2.0+2.0+0.2, giving you 4.2, which is not what we get when adding just the 2.0 & 2.0 Hope that helps! :)

[@amrojjeh]

Yasmeen Z But then the problem comes when you use the numbers in a formula. If the formula said something like 2a = b, then what stops me from doing a + a? And also the number 2 didn't come from a measurement in this case, it was a constant that I came up that fit with what I was doing. So what stops me from writing 2.0 instead of 2 to get a more precise answer? And also instead of using sig figs, why not just say that you rounded to the nearest x? Thanks for the response by the way.

[@casdxe5785]

Thanks my son made a 💯 on his test.

[@iamaperson5243]

I REPEATED THAT 3.7 PART 3 TIMES WISBHDVSJSBSHSBS I WAS LIKE WHAT

[@cameronsalehizadeh6232]

Bruh when i saw that 3.7 i instinctively went to. the comments

[@abdallababikir9154]

same

[@AmitYadav-cx9ww]

3.56=3.6

[@Mistressrichards]

Actually 3.56 would round up to 3.6

[@shirelchandra665]

what if our answer is smaller than the minimum amount of significant figures?

[@davidwiman7850]

You can add zeros if you add 1.555 and 1.445 you get 3, if you adjust for sig figs you should put 3.000

[@KAXSH]

He's probably just frustrated... I felt the same way about two minutes ago.

[@preethipritz5417]

How to add 12000+3500 to sig fig? Please help vd answer if anyone knows

[@wendysarigumba6033]

Kol, wa ghapon ko kasabot uhuhuu

[@jewelkulitzki8854]

Maoo

[@mytube1968]

Shouldn't the building w/ tower answer be 400ft, not 360ft, since 8 (and no decimals in play) is only 1 significant figure?

[@etherealwindows]

I was shocked when I saw 3.7 I thought my addition was right but it is lmaooo it’s supposed to be 3.6

[@ryostyles9904]

Okay it should be 3.6 I guess not 3.7?

[@Dudu978]

3.6* nt 3.7??

[@lenkasp]

Aren't zeros to the right of non zero numbers significant? Why do we assume that zero in 350 is not sig?

[@shirelchandra665]

it's only significant if there's a decimal point somewhere in the number. 350 is a whole number so the zero doesn't count (unless somebody clearly states/shows it is).

[@AtomFA]

there, i just left the imaginary room, im gone

[@ronharle6791]

what program are you useing

[@pixal243]

Time travel

[@ronharle6791]

+kiani 2 silver lol thanks for the speedy response

[@pixal243]

speedy not helpful

[@dougpeete2712]

Leaving training videos out here with errors only addressed with a small message in them is a problem. Reshoot it!

[@melsbells99]

How many sig figs are in the answer to this subtraction problem? 0.000152 - 0.00014 =

[@Brownkevin7]

Subtract then go to the ten thousandths spot round there your answer should only go to the ten thousandsths spot

[@quenz1036]

5

[@coachhollymitchell1980]

lol i was like WHY IS IT 3.7????????

[@ahsanmohammed1]

Mistake at 3:01 where he rounded to 3.7 instead of 3.6 is not acceptable for KZbin courses. Sorry.

[@sarahcouture1794]

not rounded to 359? why 360?

[@C4shaRaM4]

Have you found the reason?

[@rinnyrr]

I’m still confused

[@brainphelps1994]

ok what is the answer in significant figures to 6.92 + .082? This is a hard question

[@jim4686]

7.0

[@hilator4657]

7.00

[@sossoreal24]

7

[@gillian2472]

so y'all are telling me this uploaded 9 years ago👁👄👁